Nearly every wrong part we see traces back to the same moment: someone had a number that was close, and ordered it. Here is the method that avoids it.
1. Start at the model plate, not the part
The most reliable route to the right part is the equipment model, not the number stamped on the old component. Old parts get superseded, restamped and cross-branded. Model plates do not.
- Pool and spa pumps — on the motor, usually the top or the end opposite the shaft.
- Outboards — on the transom bracket or under the cowling.
- Sterndrives — on the transom assembly inside the boat.
- Industrial pumps — on the casing or the bearing frame.
Photograph it. Plates corrode and become unreadable exactly when you need them.
2. Note every suffix
Suffixes are not decoration. On a Hayward, TL means twist-lock cord. W3 marks a later production run. 2S means two-speed. On Sta-Rite seals, SS denotes a stainless variant. Dropping a suffix when you search is how people end up on the wrong side of a fitment list.
3. Understand what a cross-reference is telling you
When a listing shows several numbers — "shaft seal 354545 / 354545S / 17304-0100" — those are the same physical part under different manufacturer, era or distributor numbering. Any of them identifies the right seal.
This runs deep in some ranges. See our guides to the Sta-Rite U9-358 family and to Johnson, Evinrude, OMC and Volvo Penta, where one part carries four brand names.
4. When the number is gone entirely
Corroded plate, missing label, no paperwork. Send us:
- A photo of the equipment, including any visible plate
- A photo of the old part beside a ruler or coin for scale
- The brand, if you know it, and roughly how old the equipment is
- What the part seals — pump lid, housing, shaft, diffuser
Cross-referencing obsolete parts is most of what we do. We would far rather spend ten minutes identifying it than have you order twice.
A word on standard sizes
If your o-ring is a standard catalogue size — AS568, metric, ISO 3601, JIS B2401, BS 4518 or SMS 1588 — you can order by size directly. Note that standard catalogue sizes ship as final sale, because the full dimensions and material are published on the listing and you are selecting by measurement rather than by fitment. Equipment-specific parts ordered against a model or OEM number carry our standard 30-day return policy.
If you are unsure which category you are in, ask before ordering.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used solely to identify the equipment our replacement parts fit.